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How low can you go? Changing the resolution of novel complex objects in visual working memory according to task demands.

Allon AS, Balaban H, Luria R - Front Psychol (2014)

Bottom Line: Previous studies that investigated the trade-off between quantity and resolution in visual WM yielded mixed results for simple familiar stimuli.Our findings indicate that the resolution for novel complex objects can be increased but not decreased according to task demands, suggesting that minimal resolution is required in order to maintain these items in visual WM.These findings support studies claiming that capacity and resolution in visual WM reflect different mechanisms.

View Article: PubMed Central - PubMed

Affiliation: The School of Psychological Sciences, Tel-Aviv University Tel-Aviv, Israel.

ABSTRACT
In three experiments we manipulated the resolution of novel complex objects in visual working memory (WM) by changing task demands. Previous studies that investigated the trade-off between quantity and resolution in visual WM yielded mixed results for simple familiar stimuli. We used the contralateral delay activity as an electrophysiological marker to directly track the deployment of visual WM resources while participants preformed a change-detection task. Across three experiments we presented the same novel complex items but changed the task demands. In Experiment 1 we induced a medium resolution task by using change trials in which a random polygon changed to a different type of polygon and replicated previous findings showing that novel complex objects are represented with higher resolution relative to simple familiar objects. In Experiment 2 we induced a low resolution task that required distinguishing between polygons and other types of stimulus categories, but we failed in finding a corresponding decrease in the resolution of the represented item. Finally, in Experiment 3 we induced a high resolution task that required discriminating between highly similar polygons with somewhat different contours. This time, we observed an increase in the item's resolution. Our findings indicate that the resolution for novel complex objects can be increased but not decreased according to task demands, suggesting that minimal resolution is required in order to maintain these items in visual WM. These findings support studies claiming that capacity and resolution in visual WM reflect different mechanisms.

No MeSH data available.


Related in: MedlinePlus

The CDA wave (timed locked to the memory array) and mean amplitude in μV for one color, one polygon and three colors for (A) Experiment 1, (B) Experiment 2, and (C) Experiment 3. The gray bar above the x-axis indicates the time range for calculating the mean amplitude. (D) The CDA mean amplitude in μV for the three polygons condition in Experiment 1 and 3. 95% confidence intervals were calculated according to Loftus and Masson (1994).
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Figure 3: The CDA wave (timed locked to the memory array) and mean amplitude in μV for one color, one polygon and three colors for (A) Experiment 1, (B) Experiment 2, and (C) Experiment 3. The gray bar above the x-axis indicates the time range for calculating the mean amplitude. (D) The CDA mean amplitude in μV for the three polygons condition in Experiment 1 and 3. 95% confidence intervals were calculated according to Loftus and Masson (1994).

Mentions: The CDA waveforms and mean CDA amplitude values for one color, one polygon, and three colors for all three experiments are presented in Figures 3A–C. The CDA mean amplitude for three polygons in Experiment 1 and 3 are presented in Figure 3D. An ANOVA with stimulus-type (polygons, color squares) and set-size (1 and 3) as within-subject variables with the CDA mean amplitude as a dependent variable showed a significant main effect for set-size, F(1,9) = 31.28, MSE = 0.35, p < 0.001, = 0.77. The main effect for stimulus-type was not significant, F(1,9) = 1.17, MSE = 0.10, p > 0.3, = 0.11. The interaction for stimulus-type and set-size was significant, F(1,9) = 8.03, MSE = 0.12, p <0.05, = 0.47, such that the set-size effect was larger for colors then for polygons. Planned comparisons confirmed this pattern and showed that the CDA amplitude for three colors was significantly higher than for one color, F(1,9) = 29.18, MSE = 0.31, p <0.001, = 0.76, indicating a set-size effect for simple objects (Vogel and Machizawa, 2004; Vogel et al., 2005; McCollough et al., 2007; Gao et al., 2009; Luria et al., 2010). In addition, we found a set-size effect for polygons such that the CDA amplitude for three polygons was significantly higher than for one polygon, F(1,9) = 17.57, MSE = 0.15, p <0.01, = 0.66, indicating that one polygon did not exhaust WM capacity.


How low can you go? Changing the resolution of novel complex objects in visual working memory according to task demands.

Allon AS, Balaban H, Luria R - Front Psychol (2014)

The CDA wave (timed locked to the memory array) and mean amplitude in μV for one color, one polygon and three colors for (A) Experiment 1, (B) Experiment 2, and (C) Experiment 3. The gray bar above the x-axis indicates the time range for calculating the mean amplitude. (D) The CDA mean amplitude in μV for the three polygons condition in Experiment 1 and 3. 95% confidence intervals were calculated according to Loftus and Masson (1994).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3975110&req=5

Figure 3: The CDA wave (timed locked to the memory array) and mean amplitude in μV for one color, one polygon and three colors for (A) Experiment 1, (B) Experiment 2, and (C) Experiment 3. The gray bar above the x-axis indicates the time range for calculating the mean amplitude. (D) The CDA mean amplitude in μV for the three polygons condition in Experiment 1 and 3. 95% confidence intervals were calculated according to Loftus and Masson (1994).
Mentions: The CDA waveforms and mean CDA amplitude values for one color, one polygon, and three colors for all three experiments are presented in Figures 3A–C. The CDA mean amplitude for three polygons in Experiment 1 and 3 are presented in Figure 3D. An ANOVA with stimulus-type (polygons, color squares) and set-size (1 and 3) as within-subject variables with the CDA mean amplitude as a dependent variable showed a significant main effect for set-size, F(1,9) = 31.28, MSE = 0.35, p < 0.001, = 0.77. The main effect for stimulus-type was not significant, F(1,9) = 1.17, MSE = 0.10, p > 0.3, = 0.11. The interaction for stimulus-type and set-size was significant, F(1,9) = 8.03, MSE = 0.12, p <0.05, = 0.47, such that the set-size effect was larger for colors then for polygons. Planned comparisons confirmed this pattern and showed that the CDA amplitude for three colors was significantly higher than for one color, F(1,9) = 29.18, MSE = 0.31, p <0.001, = 0.76, indicating a set-size effect for simple objects (Vogel and Machizawa, 2004; Vogel et al., 2005; McCollough et al., 2007; Gao et al., 2009; Luria et al., 2010). In addition, we found a set-size effect for polygons such that the CDA amplitude for three polygons was significantly higher than for one polygon, F(1,9) = 17.57, MSE = 0.15, p <0.01, = 0.66, indicating that one polygon did not exhaust WM capacity.

Bottom Line: Previous studies that investigated the trade-off between quantity and resolution in visual WM yielded mixed results for simple familiar stimuli.Our findings indicate that the resolution for novel complex objects can be increased but not decreased according to task demands, suggesting that minimal resolution is required in order to maintain these items in visual WM.These findings support studies claiming that capacity and resolution in visual WM reflect different mechanisms.

View Article: PubMed Central - PubMed

Affiliation: The School of Psychological Sciences, Tel-Aviv University Tel-Aviv, Israel.

ABSTRACT
In three experiments we manipulated the resolution of novel complex objects in visual working memory (WM) by changing task demands. Previous studies that investigated the trade-off between quantity and resolution in visual WM yielded mixed results for simple familiar stimuli. We used the contralateral delay activity as an electrophysiological marker to directly track the deployment of visual WM resources while participants preformed a change-detection task. Across three experiments we presented the same novel complex items but changed the task demands. In Experiment 1 we induced a medium resolution task by using change trials in which a random polygon changed to a different type of polygon and replicated previous findings showing that novel complex objects are represented with higher resolution relative to simple familiar objects. In Experiment 2 we induced a low resolution task that required distinguishing between polygons and other types of stimulus categories, but we failed in finding a corresponding decrease in the resolution of the represented item. Finally, in Experiment 3 we induced a high resolution task that required discriminating between highly similar polygons with somewhat different contours. This time, we observed an increase in the item's resolution. Our findings indicate that the resolution for novel complex objects can be increased but not decreased according to task demands, suggesting that minimal resolution is required in order to maintain these items in visual WM. These findings support studies claiming that capacity and resolution in visual WM reflect different mechanisms.

No MeSH data available.


Related in: MedlinePlus